Magnetic properties of BaTiO₃ and BaTi_{1鈭?span style='font-style: italic'>x}M_xO₃ (M=Co, Fe) nanocrystals by hydrothermal method

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• 作者：Lihong Yang ; Hongmei Qiu ; Liqing Pan ; Zhengang Guo ; Mei Xu ; Jinhua Yin ; Xuedan Zhao
• 关键词：Nanostructure ; Chemical synthesis ; Magnetic property
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：January, 2014
• 年：2014
• 卷：350
• 期：Complete
• 页码：1-5
• 全文大小：1288 K

文摘

BaTiO₃ and BaTi_1鈭?em>xM_xO₃ (M=Co, Fe) nanocrystals were prepared by hydrothermal method. X-ray diffraction analysis indicated that all of the samples were of single-phase with tetragonal perovskite structure. The BaTiO₃ prepared exhibited weak ferromagnetism rather than diamagnetism, probably due to the oxygen vacancies at the surface. Paramagnetism was observed for all BaTi_1鈭?em>xCo_xO₃ samples with 0.05鈮?em>x鈮?.25. The Curie-Weiss fit revealed the paramagnetic moment per Co ion were 4.09 渭_B, 4.12 渭_B, and 4.36 渭_B for x=0.15, 0.20, and 0.25 respectively. Room temperature hysteresis loops of the Fe-doped BaTiO₃ samples were observed at the doping level x between 0.2 and 0.5. The saturation magnetization firstly increased with increasing Fe content, but gradually decreased. The divergence was observed in the temperature dependence of the field cooling (FC) and zero-FC (ZFC) magnetization curves, indicating a spin-glass behavior arising from micromagnetic state, i.e. the mixing of ferromagnetic, and antiferromagnetic phases. The observed ferromagnetism may originate from the coupling between the secondary-nearest Fe ions and the antiferromagnetism may be due to the coupling between the nearest Fe ions. The ferromagnetic coupling competes with the antiferromagnetic coupling. Therefore, the ferromagnetic properties are predominant when the Fe doping level are at a certain range.